Bicycle hubs, especially those that have internal gear teeth for a backpedal brake with freewheel as well as internal gear teeth as the mating part for a hub gear, have until now been forged from a tube and finished by machining. The conventional method for producing a bicycle hub comprises steps of provisioning internal gear teeth and drilling holes in formed flanges, into which spokes are then mounted. Internal ball tracks at the ends of the bicycle hub are also finished by machining, specifically by turning.
These machining operations require considerable effort, which leads to correspondingly high finishing costs. Consequently, known bicycle hubs are exceptionally expensive when compared with other parts of a bicycle.
Furthermore, these forged bicycle hubs are relatively heavy, as their wall must be sufficiently thick to be shaped by means of forging and machining. However, this relatively high weight is contrary to a general desire to make bicycle parts as light weight as possible.
In order to avoid these disadvantages, it is recommended in DE 2906627 C2 (also published as U.S. Pat. No. 4,351,569) that a bicycle hub be formed as a sheet metal part with two hub elements, each of which is manufactured by deep drawing. Both the hub elements are connected to one another either by positive locking or bonding, whereby pressing or riveting is recommended for achieving positive locking, and adhesion or welding for bonding.
Deformation is necessary for pressing, which can affect the concentricity of the bicycle hub. Welding on the other hand leads to warping of the hub elements, which can only be rectified by subsequent straightening. In either case, additional cost-increasing operations are necessary in order to connect the two hub elements with one another.
Furthermore, the usual construction leads to the ball tracks having different diameters, which leads to drawbacks with respect to usage. In particular, it is not possible to use either of the hub elements as the base for different hub gears mounted on the inside of a bicycle hub.
Any desired optimization in the bicycle hub's weight is restricted by the loads arising in the ball track area during running, which requires the hub elements to have a certain wall thickness. This wall thickness is substantially constant across known bicycle hubs, i.e. the wall thickness is determined only by the load discussed above.
Another drawback of known bicycle hub is that both the wheel flanges are different with regard to their distance from the respective front side of the bicycle hub, such that one end of the bicycle hub projects outward beyond the attached spokes.
Both flanges shown and described in U.S. Pat. No. 2,997,145 are affixed to the sleeve of the bicycle hub also mainly by welding or soldering. To this extent, the aforementioned drawbacks that arise from bonding also arise with this bicycle hub.